1. Field of the Invention
The present invention generally relates to DC power supplies and in particular to a plug-in power supply for converting a main supply voltage into an operating voltage, comprising a housing having arranged therein an electronic circuit for voltage conversion, and at least two primary contact pins which are movable between an operating position, in which they are adapted to be inserted into the main supply socket and in which they extend substantially at right angles to one of the lateral surfaces of the housing, and a position of rest on at least one of said lateral surfaces, the primary contact pins being arranged substantially parallel to said at least one lateral surface in said position rest.
2. Description of the Related Art
As outlined in FIG. 1, conventional plug-in power supplies, which convert the main supply voltage (normally 110 or 230 volt) into an operating voltage (normally a so-called extra-low safety voltage), comprise a housing 102 having essentially the shape of a rectangular parallelepiped and including a cover surface 110, a base surface 111, as well as four lateral surfaces 116. The housing 102 has arranged therein an electronic circuit for voltage conversion. In addition, the plug-in power supply 100 is normally provided with an electric connecting line 104 which is adapted to be inserted via a plug 106 into a plug socket of a load, and a primary contact 108 arranged on the base surface 111 and adapted to be inserted into a main supply socket. The trend towards size optimization of mobile loads, such as mobile phones, palmtops or the like, makes it necessary that also the accessories required, such as a charging set, which can be realized in the form of a plug-in power supply according to FIG. 1, are miniaturized to the greatest degree possible. In particular on the Asian market, a volume optimization of technical devices is a feature which decisively influences the buyer""s decision. The reduction of size is limited by the electric components which have to be used and by the standards which have to be observed with regard to insulation distances and creeping distances. It follows that narrow limits are set to a more far-reaching miniaturization of the plug-in power supply, especially in the operating condition, as can be seen for instance from DE 198 35 161 C1 and DE 198 45 962 C1.
Such conventional plug-in power supplies are known for instance from DE 297 08 589 U1 and U.S. Pat. No. 5,901,056.
For accommodating the primary contact pins 108 on the base surface 111, a recess is provided, which extends comparatively far into the interior of the housing. This has the effect that the volume in the housing interior that can be used for the electric components is reduced by mechanical components.
A further drawback of the arrangement outlined in FIG. 1 is the disadvantageous position of the plug-in power supply 100 in a main supply socket in which neighboring sockets may be covered.
It is therefore the object of the present invention to provide a plug-in power supply for converting a main supply voltage into an operating voltage, said plug-in power supply being reduced still further in size and adapted to be handled easily and safely.
According to one embodiment, a geometric arrangement of the primary contact pins with respect to each other in their position of rest differs from a geometric arrangement of the primary contact pins in their operating position.
A substantial advantage of said plug-in power supply according to the present invention is that, by displacing the primary contact pin, said primary contact pin can be moved to an extremely space-saving position of rest. In addition, the plug-in power supply according to the present invention has a smooth surface, without any projecting plug pins which may get caught up with other components during transport, when the primary contact pin is at its position of rest. By arranging the primary contact pin at right angles to a lateral surface of the plug-in power supply in the operating position, it is additionally possible to prevent neighboring sockets from being rendered inaccessible.
In order to make the plug-in power supply compatible with existing main supply sockets, same is provided with two primary contact pins, which, when occupying the operating position, are arranged at a distance from one another that conforms to the standard.
Further developments of the present invention are the subject matters of a plurality of dependent claims.
According to a preferred embodiment, the primary contact pins are adapted to be swiveled, e.g., for the purpose of transport, from the operating position, in which they are adapted to be inserted into the main supply socket, to a position of rest on at least one of the lateral surfaces of the housing. This offers the advantage that space for the contact pin is not required in the interior of the housing. The structural design of the housing is particularly simple in the case of this embodiment.
According to another preferred embodiment, one of the primary contact pins is adapted to be axially displaced from the operating position to the position of rest on one of the lateral surfaces of the housing and the other primary contact pin is adapted to be swiveled from the operating position to the position of rest on one of the lateral surfaces of the housing. This embodiment offers the possibility of a particularly far-reaching miniaturization of the plug-in power supply, when the primary contact pins are at their position of rest and handling will be particularly easy.
In order to guarantee the highest possible safety of the plug-in power supply according to the present invention, the plug-in power supply can be so conceived that the electric connection between the primary contact pin and the electronic circuit in the interior of the housing will not be established until the final operating position has been reached.
Particularly safe contact with the main supply socket will be achieved when the primary contact pin is adapted to be locked in its operating position.
According to a preferred embodiment, the housing is provided with recesses which accommodate the primary contact pin in its position of rest. This will guarantee that the surface of the plug-in power supply according to the present invention is flat and that projecting pins which may get caught up with other components are avoided.
When the primary contact pin is so conceived that it is adapted to be locked in its position of rest, this will have the advantage that it is protected against inadvertent displacement from its position of rest.
According to a preferred embodiment, the housing of the plug-in power supply according to the present invention comprises two halves which are adapted to be connected to one another. This offers the advantage of a simplified, economy-priced assembly.
In order to guarantee an increased degree of safety, the plug-in power supply according to the present invention can be equipped with a mechanical coupling device which is provided between the two primary contact pins and which forces the two pins to move simultaneously.
A particularly simple and economy-priced possibility of realizing such a coupling device is the use of gears.
The housing can be provided with an electric connecting line which is adapted to be inserted via a plug into a plug socket of a load so that, when the plug-in power supply is in operation, a connected load can be arranged remote from the power socket (e.g. a mobile phone on a table).